This invention relates to apparatus for altering the size of a television picture and, more particularly, to an apparatus which includes means for sampling incoming video signals and providing second television video signals constructed from samples of the incoming television video signals.
Recently, video synchronizers have been introduced. These synchronizers have been introduced in order to synchronize broadcast sources to the local station reference generator. A video synchronizer is an electronic unit that samples the analog input, converts it to a digital format, stores the digital data, and operates on the digital data to deliver a desired analog output which is constructed from the sampled video. It is designed to automatically lock a non-synchronous broadcast signal to a reference generator and thus allow fully synchronous treatment of the incoming video for mixing with station programs. The non-synchronous signal is digitized and stored in a memory. The data is clocked out of the memory at a rate locked to the reference sync generator (usually the local station). This synchronizer isolates the input and output video lines and the output is fully synchronous in vertical, horizontal and color phases with the reference.
These video synchronizers make possible many special effects for relatively low additional cost. Applicant's invention herein relates to the special effect of expansion or compression using apparatus like these video synchronizers by adding or eliminating samples. Applicant has found, however, that picture compression or expansion by indiscriminately adding or eliminating samples or lines is unworkable for reproducing color since such adding or eliminating disrupts the subcarrier, and randomly adding or eliminating lines disrupts the normal color sequency required for sequential lines in the NTSC television system.